Characterization of Aspergillus section Flavi isolated from organic Brazil nuts using a polyphasic approach

• Aspergillus section Flavi species from organic Brazil nuts were characterized.
• Polyphasic approach permitted the reliable identification of Aspergillus.
• Aspergillus flavus, Aspergillus nomius, Aspergillus tamarii and Aspergillus caelatus were isolated.
• A. flavus was the most predominant in organic Brazil nuts.
• A. nomius strains were able to produce high levels of aflatoxins.

Brazil nut (Bertholletia excelsa), an important non-timber forest product from Amazonia, is commercialized in worldwide markets. The main importers of this nut are North America and European countries, where the demand for organic products has grown to meet consumers concerned about food safety. Thus, the precise identification of toxigenic fungi is important because the Brazil nut is susceptible to colonization by these microorganisms. The present study aimed to characterize by polyphasic approach strains of Aspergillus section Flavi from organic Brazil nuts. The results showed Aspergillus flavus as the main species found (74.4%), followed by Aspergillus nomius (12.7%). The potential mycotoxigenic revealed that 80.0% of A. flavus were toxin producers, 14.3% of which produced only aflatoxin B (AFB), 22.85% of which produced only cyclopiazonic acid (CPA), and 42.85% produced both them. All strains of A. nomius were AFB and AFG producers and did not produce CPA. There is no consensus about what Aspergillus species predominates on Brazil nuts. Apparently, the origin, processing, transport and storage conditions of this commodity influence the species that are found. The understanding about population of fungi is essential for the development of viable strategies to control aflatoxins in organic Brazil nuts.